1. Field of the Invention
The present invention relates to a residue treatment system, a residue treatment method, and a method of a manufacturing semiconductor device which remove residue generated by dry etching for an insulating film.
2. Related Art
With an increase in processing speed of a semiconductor device such as a large-scale integrated circuit (LSI), micropatterning and high integration of elements such as transistors used in the semiconductor device are advanced. In such a semiconductor device, elements and multilayer interconnections are connected by conductive vias, contacts, and the like buried in an insulating interlayer deposited on a semiconductor substrate. For example, in order to form interconnections and conductive vias for connecting between wiring layers, trenches and via holes are formed in an insulating interlayer by dry etching such as reactive ion etching. To the side walls and the bottom surfaces of the trenches and the via holes, polymer which is a reaction product in dry etching on the insulating interlayer adheres as residue. The adhering residue causes not only an increase in resistance between wiring layers but also deterioration of a wiring metal, the conductive vias, and the like by corrosion.
Residue generated by dry etching for an insulating interlayer or the like can be selectively removed by a wet etching treatment using a etching fluid (for example, see Japanese Patent Application Laid-open No. 2005-217114). In general, the wet etching treatment in a residue removing step is performed such that the etching fluid is circulated by a circulating system. In the circulating process, residue removing treatment for a large number of semiconductor substrates can be performed by repeatedly uses the etching fluid. For this reason, number of times of waste liquid treatment is reduced to make it possible to suppress the cost of etching fluid.
In the residue removing step, residue is removed by being selectively etched. However, in fact, an insulating interlayer or the like to which residue adheres is also etched. The residue contains a reactive gas component used in dry etching, and the reactive gas component is solved in the etching fluid. The etching characteristics of the etching fluid are adversely affected by the dissolved reactive gas component. For example, in the circulating process, when residue removal is repeated, an etching rate to the insulating interlayer increases. With the increase in etching rate, processing conversion differences between trenches and via holes formed in the insulating interlayer increase. As a result, a capacitance between interconnections or wiring layers increases to deteriorate the performance of a semiconductor device.
At the present, an etching rate of an insulating film immediately before residue removal is checked each time to treat a semiconductor substrate. As a result, time required for the residue removing step increases to cause an increase in manufacturing cost.